The invention relates to a fuel injection nozzle and more particularly to an injection valve for both preliminary fuel injection as well as main fuel injection and involves a construction in which a needle valve is shiftable under pressure of the supplied fuel against the force of the closing spring with the opening stroke of the needle valve being controlled by a slide element which serves as a limiting means for the stroke of the needle valve. With such a fuel injection nozzle, the valve opening cross section in the case of engine idling and for low partial loads should be smaller than in the case of higher loads. In addition, a smaller opening cross section creates improved atomization of the fuel volume determined by the load resulting in better fuel preparation. As a consequence, the engine runs more quietly and combustion is improved.
At higher loads and rpm, however, the largest possible opening cross section should be available from the very beginning in order to maintain the volume of fuel flow required by modern, fast running Diesel engines while maintaining reasonable physical dimensions.